JPH11161753A - Communication system for moving object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the serviceability of a system by allowing a user to know a distance between a reader/writer 1 and an ID tag 3, and allowing the user to recognize a measure of a distance optimal to communication between the reader/writer 1 and the ID tag 3. SOLUTION: A position relation between a reader/writer 1 and an ID tag 3 can be captured according to a signal level received from the ID tag 3 by a reader/writer 1. Then, the reader/writer 1 having means 17 and 18 for receiving a response signal transmitted from the ID tag 3 is provided with a means 4 for detecting the reception level of the signal, a means 4 for judging whether or not the detected reception level fulfills a preliminarily set value, and outputting means 5 and 7 for outputting an acoustic signal or a visual signal for allowing a user to know that position relation between the reader/writer 1 and the ID tag 3 is appropriate when the reception level fulfills the pertinent condition. Then, the user can recognize an optimal position relation between the reader/writer 1 and the ID tag 3 according to the acoustic signal such as the presence or absence of a beep sound, or the visual signal such as the presence or absence of the light emission of a light emitting element or a message display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, such as an ID tag system or an IC card system, for performing non-contact communication between an interrogator and a transponder.

[0002]

2. Description of the Related Art A non-contact type mobile communication system for performing wireless communication between a movable transponder and an interrogator includes:
For example, a non-contact method in which wireless communication is performed between an IC card or ID tag (a transponder) that is moved by being carried by a user or attached to an object, and a fixedly installed or portable reader / writer (an interrogator). There are known IC card systems and ID tag systems. For example, when an ID tag attached to a user or an article enters a service area of the reader / writer together with the person or the article, the reader / writer transmits a request for identification data or the like,
In response to this, the ID tag returns its own identification data and the like, so that the reader / writer identifies the ID tag and identifies the person or object.

In such an ID tag system, an amplitude modulation method for amplitude-modulating a carrier wave with transmission data and wirelessly transmitting the radio wave (or an amplitude modulation method for making the amplitude correspond to a discrete level).
SK (Amplitude Shift Keying) is used, and conventionally, for example, a system configuration as shown in FIG. 4 was used. In the example shown in FIG. 4, the ID tag (responder) 3 is not provided with a power source such as a battery, and the ID tag 3 is operated by the operating power transmitted from the reader / writer (interrogator) 1 by electromagnetic induction or the like. Operates, reader / writer 1 and ID tag 3
Is a non-contact type ID tag system that performs wireless communication as described below between the antennas 10 and 30.

In this ID tag system, in a reader / writer 1, a carrier generated by a synthesizer 11 is amplitude-modulated by a modulator 12 with interrogation data or a clock, and an obtained interrogation signal is amplified by a transmission amplifier 13 to be circulated. The radio transmission is performed from the antenna 10 via the antenna 14. on the other hand,
In the ID tag 3, the interrogation signal received by the antenna 30 is amplitude-demodulated by the modem 31, and the controller 32 reads out identification data and the like from the memory 33 according to the interrogation data obtained by demodulation, and The carrier wave from the circuit 34 is amplitude-modulated by the modulator / demodulator 31 using response data (identification data or the like) output from the control unit 32 and transmitted from the antenna 30 to the reader / writer 1.

In the reader / writer 1, the antenna 1
The signal received at 0 is input to the distributor 15 via the circulator 14, the received signal is branched into two, and the first received signal is input to the first receiving circuit 17 via the phase shifter 16, The second reception signal is used as it is in the second reception circuit 18.
Enter The phase shifter 16 sets the phase of the received signal to 90
The first reception circuit 17 mixes the transmission signal output from the transmission amplifier 13 and the phase-shifted reception signal in the mixer 19 to extract the difference, and removes unnecessary components in the filter 20. The extracted signal is amplified by the receiving amplifier 21 and output to the combining amplifier 22. On the other hand, in the second receiving circuit 18, the mixer 23 mixes the transmission signal output from the transmission amplifier 13 and the reception signal that has not been phase-shifted to extract a difference, and the filter 24 removes unnecessary components. The extracted signal is amplified by the reception amplifier 25 and output to the synthesis amplifier 22.

[0007] The combining amplifier 22 combines the two input extracted signals, and the converter 26 converts the combined analog-level extracted signal into a digital signal to obtain response data from the ID tag 3.

Here, in the ID tag system for supplying the operating power from the reader / writer 1 to the ID tag 3 as described above, it is not possible to transmit too much operating power to the ID tag 3, so that the reader / writer 1 Only at a level lower than the signal level transmitted to the tag 3, the ID tag 3
Unable to receive signals from For this reason, the signal received by the reader / writer 1 from the ID tag 3 is canceled by the transmission signal by simply performing the reception processing, and the reader / writer 1 cannot demodulate the received signal.

In order to solve such a problem, the above-described ID tag system employs a double-balanced mixer 1
Input a transmission signal at a certain level to LO terminals 9 and 23,
By canceling its own transmission signal riding on the reception signal input from the RF terminals of the double balance mixers 19 and 23, only the signal component transmitted by the ID tag 3 is extracted.

Further, in the ID tag system, since the ID tag (responder) 3 moves even during communication and the distance from the reader / writer (interrogator) 1 changes, the reader / writer 1
Changes the phase of the signal it receives. For this reason, only one of the first receiving circuit 17 or the second receiving circuit 18 changes the received signal input to the receiving circuit according to this distance change as shown by a solid line in FIG. Wavelength), λ / 2 = 1
The level extremely decreases at a cycle of 80 degrees, and a state where the received signal cannot be demodulated occurs. Therefore, in the ID tag system as described above, the first receiving circuit 17
The received signal is input to the second receiving circuit 18 and the second receiving circuit 18 with their phases shifted by 90 degrees, thereby compensating for the extremely low level as described above with the other received signal as shown by the broken line in FIG. The outputs of the receiving circuits 17 and 18 are combined to demodulate the amplitude of the received signal as a whole.

[0010]

Here, in the above-described mobile communication system, it is desired to notify how long the transponder is located with respect to the interrogator and that optimal communication can be performed between the two. There is a request that. For example, by notifying the user carrying the transponder how far the transponder should be from the interrogator to achieve optimal communication, the interrogator and the transponder can communicate at an appropriate distance. By making the user aware of the standard, the ease of use of the system can be improved. However, the above-mentioned conventional mobile communication system has a problem that such a demand cannot be met.

SUMMARY OF THE INVENTION The present invention has been made in view of such a demand, and provides a mobile communication system capable of outputting in an easy-to-perceive form that the positional relationship between an interrogator and a transponder is appropriate. With the goal.

[0012]

To achieve the above object, the present invention focuses on the point that the positional relationship between an interrogator and a transponder can be grasped by the signal level received by the interrogator from the transponder. In a non-contact type mobile communication in which wireless communication is performed between the interrogator and the movable transponder, the interrogator outputs an audible or visually recognizable signal according to the level of a signal received from the transponder. By doing
The user perceives the positional relationship where the interrogator and the transponder can communicate optimally.

That is, in the mobile communication system according to the present invention, the interrogator includes: means for receiving a response signal transmitted from the transponder; means for detecting a reception level of the signal; Means for judging whether or not a predetermined value is satisfied, and an audio signal for notifying a user that the positional relationship between the interrogator and the transponder is appropriate when the detected reception level satisfies the predetermined value. Output means for outputting at least one of a visual signal. Therefore, an acoustic signal such as the presence or absence of a beep sound or the output of a message voice, or a visual signal such as the presence or absence of the light-emitting element, the number of light-emitting elements, and the display of a message, etc., tells the user the interrogator and the transponder. The optimum positional relationship can be easily perceived.

According to the present invention, when the transponder has a built-in battery or the like serving as an operating power source, the transponder does not have such an operating power source, and the operating power transmitted from the interrogator is not used. It can be applied to any case of receiving power by contact, but especially in the latter case, the distance between the interrogator and the transponder is related to the amount of power received by the transponder. There is an advantage that the user can easily perceive the optimum positional relationship for operating the container normally.

According to the present invention, the desired object can be achieved by outputting either the auditory signal or the visual signal. However, by outputting both, the auditory signal and the visual signal are output. Both may be made to perceive the optimal positional relationship between the interrogator and the transponder. Also, the present invention
As a preferred example, an I tag composed of an ID tag and a reader / writer
The present invention is applied to a D tag system, but is not limited to this. For example, a system that wirelessly communicates between an installed interrogator and a card or a batch-type movable transponder, such as a system that relatively moves between communication devices. The present invention can be widely applied to a system that performs wireless communication, and an intended purpose can be achieved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to a non-contact ID tag system will be described with reference to the drawings.
The same reference numerals are given to the same functional parts as those of the conventional non-contact type ID tag system shown in FIG. FIG. 1 shows a configuration of a non-contact ID tag system according to a first embodiment of the present invention. The main part of this example is compared with the conventional non-contact ID tag system shown in FIG. To explain, a reader / writer (interrogator) 1 has a position discriminator 4 that determines whether the positional relationship between the reader / writer 1 and the ID tag 3 is appropriate based on the signal level received from the ID tag (responder) 3.
And a display output unit 7 for outputting a visual signal according to the determined reception level.

In the ID tag system of this embodiment, the ID
The tag (responder) 3 is not provided with a power source such as a battery, and the ID tag 3 is operated by operating power transmitted from the reader / writer (interrogator) 1 by electromagnetic induction or the like, and the reader / writer 1 and the ID tag 3 are operated. The wireless communication is performed between the antennas 10 and 30 using the antennas 10 and 30. For example, the antenna 10 provided in the reader / writer 1 is also used for power transmission, or the antenna for power transmission is separately provided in the reader / writer 1, and the antenna 30 provided on the ID tag 3 is also used for power reception. Alternatively, a power receiving antenna is separately provided in the ID tag 3, and the operating power is transmitted from the reader / writer 1 to the ID tag 3 in a non-contact manner by electromagnetic induction or the like between the power antennas.

Data communication in the ID tag system of the present embodiment is also performed in the same manner as in the conventional example. In the reader / writer 1, the transmission carrier generated by the synthesizer 11 is amplitude-modulated by the modulator 12 with interrogation data or the like, and obtained. The received interrogation signal is amplified by the transmission amplifier 13 and wirelessly transmitted from the antenna 10 via the circulator 14. On the other hand, the ID tag 3 receives operating power by a power receiving circuit (not shown), operates by this power, amplitude-demodulates the interrogation signal received by the antenna 30 by the modulator / demodulator 31, and responds to the received interrogation data. The controller 32 writes data to and reads data from the memory 33. Then, response data (identification data and the like) to the query data is output from the control unit 32 to the modem 31, and the modem 35 amplitude-modulates the carrier oscillated by the internal oscillator 34 with the response data, and obtains a response signal. Is wirelessly transmitted from the antenna 30 to the reader / writer 1.

In the reader / writer 1, the antenna 1
0 is input to the distributor 15 via the circulator 14, the response signal (received signal) is branched into two, and one of the response signals is converted to the first signal via the phase shifter 16.
And the other response signal is input to the second receiving circuit 18 as it is. The phase shifter 16 shifts the phase of one of the response signals by 90 degrees, and the first reception circuit 17
The mixer 19 mixes the interrogation signal input at a certain level from the transmission amplifier 13 and the phase-shifted response signal to extract the difference, removes unnecessary components by the filter 20, and converts the extracted signal to the reception amplifier. The signal is amplified at 21 and output to the synthesis amplifier 22. On the other hand, in the second receiving circuit 18, the interrogation signal input from the transmission amplifier 13 at a constant level and the response signal that is not phase-shifted are mixed by the mixer 23 to extract the difference, and the filter 24 removes unnecessary components. Then, the extraction signal is amplified by the reception amplifier 25 and output to the synthesis amplifier 22.

That is, the double balance mixers 19, 2
In each LO terminal of No. 3, an interrogation signal is input from the transmission amplifier 13 at a fixed level, and the double balance mixers 19 and 23 cancel their own interrogation signals riding on the response signal input from the RF terminals. Then, only the signal component transmitted by the ID tag 3 is extracted. Then, the combining amplifier 22 combines the two input extracted signals, and the converter 26 converts the combined analog-level extracted signal into a digital signal to obtain response data from the ID tag 3.

Here, in the above data receiving process,
The output from the synthesizing amplifier 22 is also input to the position discriminator 4, and the position discriminator 4 uses the reader / writer 1 based on the reception levels of the response signals received by the first receiving circuit 17 and the second receiving circuit 18. It is determined whether the positional relationship between the ID tag 3 and the ID tag 3 is appropriate for wireless communication and power transmission. Then, the position discriminator 4 outputs a display output signal corresponding to the discrimination result to the display output device 5, and the display output device 5 outputs a visual signal according to the display output signal.

More specifically, the display output unit 5 includes a lamp, a light emitting element (LED), a liquid crystal display panel, and the like. The positional relationship between the reader / writer 1 and the ID tag 3 is determined according to the display output signal. When appropriate, an LED or the like emits light, or a message indicating that the ID tag is at the optimum position, such as "ID tag is at the optimum position" is displayed on the liquid crystal display panel. Alternatively, a plurality of LEDs or the like may be provided, and the number of light emission may change as the position approaches the optimum position. Therefore, when the signal reception level of the reader / writer 1 is relatively low when the ID tag 3 is relatively far away, and when the signal reception level of the reader / writer 1 is relatively high when the ID tag 3 is relatively close. Between
When the positional relationship between the ID tag 3 and the reader / writer 1 becomes appropriate, the user can recognize a guideline of the optimum distance between the ID tag 3 and the reader / writer 1 by the visual signal output from the display output device 7. it can.

In addition, according to the present invention, the amount of light emitted from one LED is changed according to the positional relationship between the ID tag 3 and the reader / writer 1, and the amount of light emitted from the EL panel is changed to change the backlight of the liquid crystal display panel. It is possible to adopt various modes such as changing the brightness of the image, changing the color of the liquid crystal display panel, and the like, in short, so that the user can visually recognize that the optimum positional relationship exists. What should I do?

Here, a position discriminator 4 for discriminating whether the positional relationship between the reader / writer 1 and the ID tag 3 is appropriate for wireless communication and power transmission is as shown in FIG. It can be configured. A position discriminator 4 shown in FIG. 2A detects a reception level from a reception signal output from the synthesis amplifier 22 and detects a peak position of the reception level based on the detected reception level. And a peak detection unit 42 that performs the operation. The peak detection unit 42 detects the detected change in the reception level by a process such as differentiation, and when the reception level reaches a value at which the reception level reaches the maximum peak, or a value at which the reception level approaches the maximum peak. Then, a display output signal for causing the user to display and output the visual signal as described above is output to the display output device 5.

The position discriminator 4 shown in FIG.
A reception level detection unit 41 that detects a reception level from a reception signal output from the synthesis amplifier 22 and a threshold value as a reception level obtained when the ID tag 3 and the reader / writer 1 have an optimal positional relationship are stored in advance. Memory 43,
A determining unit that compares the detected reception level with a threshold value stored in the memory to determine whether the detected reception level is in an optimum state; The peak detection unit 42 sequentially monitors the detected reception level, and when the reception level reaches a threshold value or when the reception level exceeds the threshold value, the above-described visual signal is used by the user. And outputs a display output signal to be output to the display output device 5.

FIG. 3 shows a configuration of a non-contact ID tag system according to a second embodiment of the present invention. The main part of this example is compared with the non-contact ID tag system shown in FIG. More specifically, the reader / writer (interrogator) 1 is provided with an audio output device 6 that outputs an audio signal according to the result of the discrimination by the position discriminator 4. The non-contact type I shown in FIG.
Functional parts similar to those of the D tag system are denoted by the same reference numerals, and redundant description will be omitted. In the present embodiment, when the position discriminator 4 determines that the positional relationship between the ID tag 3 and the reader / writer 1 is appropriate, the sound output device 6 responds to the sound output signal output from the position discriminator 4. Outputs an acoustic signal.

More specifically, the sound output device 6 includes a speaker, a buzzer, and the like. When the positional relationship between the reader / writer 1 and the ID tag 3 is appropriate in accordance with the sound output signal, the sound output device 6 outputs the sound from the speaker or the like. Outputs a predetermined sound. Therefore, when the signal reception level of the reader / writer 1 is relatively small when the ID tag 3 is relatively far away,
Is relatively close to the position when the signal reception level of the reader / writer 1 is relatively high, and if the positional relationship between the ID tag 3 and the reader / writer 1 is appropriate, the auditory output from the sound output device 6 The signal allows the user to recognize the optimal distance between the ID tag 3 and the reader / writer 1.

In addition, according to the present invention, according to the positional relationship between the ID tag 3 and the reader / writer 1, a guide of the distance is output by voice, for example, "ID tag is at an optimum position". Alternatively, various modes such as changing the output sound from a speaker or the like according to the positional relationship between the ID tag 3 and the reader / writer 1 can be adopted. In short, the user can determine the optimal positional relationship by hearing. What is necessary is just to be able to recognize.

In the above description, the reader / writer 1 is installed and fixed. However, in the present invention,
The reader / writer 1 (interrogator) may be fixed or portable at all times, and may be installed at an arbitrary place, and may be a portable type.

[0030]

As described above, according to the present invention,
Since the optimal positional relationship between the interrogator and the transponder is notified by the auditory signal or the visual signal, the user can easily recognize the standard of the positional relationship. For this reason, for example, the user carrying the ID tag or the IC card can obtain an indication as to how much positional relationship can be established to communicate with the reader / writer in an optimal state. In practical use of the ID tag system and the IC card system, the user's embarrassment can be eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a non-contact ID tag system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a position discriminator according to the present invention.

FIG. 3 is a non-contact type ID according to another embodiment of the present invention.
It is a block diagram of a tag system.

FIG. 4 is a diagram showing a configuration of a conventional non-contact ID tag system.

FIG. 5 is a graph showing a phase change of a received signal level.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reader / writer (interrogator), 3 ... ID tag (responder), 4 ... Position discriminator, 5 ... Display output device, 6 ... Sound output device, 10 ... Antenna, 1
7 ... first receiving circuit, 18 ... second receiving circuit,
30 ... antenna,

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshihito Hirooka 3-14-20 Higashinakano, Nakano-ku, Tokyo Kokusai Denki Co., Ltd. (72) Inventor Tomoki Takazoe 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] 1. A non-contact type mobile communication system for performing wireless communication between an interrogator and a movable transponder, wherein the interrogator receives a response signal transmitted from the transponder. Means for detecting the reception level of the signal, means for determining whether the detected reception level satisfies a preset value, and questioning the user when the detected reception level satisfies the preset value. Output means for outputting a visual signal indicating that the positional relationship between the communication device and the transponder is appropriate. 2. A non-contact type mobile communication system for performing wireless communication between an interrogator and a movable transponder, wherein the interrogator receives a response signal transmitted from the transponder. Means for detecting the reception level of the signal, means for determining whether the detected reception level satisfies a preset value, and questioning the user when the detected reception level satisfies the preset value. Output means for outputting an audio signal indicating that the positional relationship between the communication device and the transponder is appropriate. 3. The mobile communication system according to claim 1, wherein the transponder operates by contactlessly receiving the power transmitted from the interrogator and operating between the interrogator and the interrogator. A mobile communication system for performing wireless communication.